In an effort to design efficient low-cost polymers for use in organic photovoltaic cells the easily prepared donor-acceptor-donor triad of a either cis-benzobisoxazole, transbenzobisoxazole or trans-benzobisthiazole flanked by two thiophene rings was combined with the electron-rich 4,8-bis(5-(2-ethylhexyl)-thien-2-yl)-benzo[1,2-b:4,5-b']dithiophene. The electrochemical, optical, morphological, charge transport, and photovoltaic properties of the resulting terpolymers were investigated. Although the polymers differed in the arrangement and/or nature of the chalcogens, they all had similar highest occupied molecular orbital energy levels (-5.2 to -5.3 eV) and optical band gaps (2.1-2.2 eV). However, the lowest unoccupied molecular orbital energy levels ranged from -3.1 to -3.5 eV. When the polymers were used as electron donors in bulk heterojunction photovoltaic devices with PC71BM ([6,6]-phenyl C-71-butyric acid methyl ester) as the acceptor, the trans-benzobisoxazole polymer had the best performance with a power conversion efficiency of 2.8%. (C) 2015 Wiley Periodicals, Inc.